When creating multilayer optical disks with a large number of information layers, one of the main problems is addressing the information layer during a readout procedure. In prior-art one-layer and two-layer optical disks, the reading radiation is furnished to the information layer via flat surface of the disk. However, if the number of layers increases, there occur big problems with determination of the number of information layer from which the signal with recorded data is received. This problem is solved by directing the reading radiation to a special ducting layer located near the disk addressable information layer via its lateral surface (cylindrical surface).
Previously known is a multilayer optical disk (USA patent application No.2008/0305324 A1 published Nov. 12, 2008, B32B 17/10) including several information layers separated from one another by at least two insulating layers made of polymers with different mechanical properties. One of the insulating layers possesses an increased rigidity at the expense of a filler introduced into it, and its thickness is from 5 to 15 μm, and the other possesses an increased elasticity and has a thickness of 10 to 50 μm. The said structure ensures excellent mechanical properties of a multilayer optical disk, namely: deformational stability. However, this disk is not intended for use in readout devices having high addressing accuracy, since its structure does not assume availability of a waveguide layer and does not envisage a possibility of introducing the reading radiation via its lateral surface.
Previously known is a multilayer optical disk (U.S. Pat. No. 7,449,278 B2, published Nov. 11, 2008, G1 1B 7/24) including groups of layers spaced in series where each group consists of three layers: the information layer where under the effect of radiation with a wavelength λ1 there occur photochemical processes resulting in variation of optical properties of the material the information layer is composed of; the photochromic layer which the reflecting capability is increased under the effect of radiation with a wavelength λ2 and the waveguide layer intended for propagation therein of radiation with a wavelength λ2 and introduced into a multilayer disk via its lateral surface. The data addressing reliability in this disk is higher than that of aforesaid analog since in the readout mode, the reflecting photochromic layer isolates the data receiver from the signals coming to it from underlying information layers, but the signals coming from the overlying non-addressable information layers can still reach the receiver thus reducing the data readout reliability.
A multilayer optical disk (U.S. Pat. No. 6,045,888, published Apr. 4, 2000, B32B 3/00) is the closest one to the claimed invention by its technical essence, it consists of a series of alternating layers of optically transparent materials combined into groups incorporating a layer of glass of 140 μm in thickness with a refraction index n1=1.515 enclosed between a polymer with a refraction index n2 satisfying the relationship n2<n1 and a layer of photochromic material with a refraction index n3=1.47, which can change its optical properties under the effect of radiation with a wavelength λ1 and acquire a property of fluorescenting under the effect of radiation with a wavelength λ2 at a wavelength λ3. During the information readout, the radiation with a wavelength λ2 is directed to this multilayer optical disk via its lateral surface, i.e., to the glass surface. During waveguide propagation of light in a glass, an insignificant portion of radiation power, only, penetrates the photochromic material information layer in the form of evanescent mode. Therefore, the value of the signals, arriving at the radiation receiver at a wavelength λ3 from those sections (pixels) of the glass-adjoining information layer, which were previously illuminated by radiation with a wavelength λ1 and which contain the information bits, is very small. In order to increase the signal-to-noise ratio and obtain a reliable registration of radiation at a wavelength λ3, the lateral dimensions of pixels in the photochromic layer plane should be increased, and this results in a decrease of information capacity of the multilayer optical disk.